It is generally known to form terry loops extending inwardly in the high-splice area, heel, sole and toe of a sock to provide a "cushion foot" in the sock. Examples of such socks are illustrated in U.S. Pat. Nos. 2,375,684; 2,421,817; and 2,435,770. However, this known type of "cushion foot" sock has the same general outer appearance in both the terry loop areas as well as in the adjacent areas without terry loops because the yarn forming the terry loops is usually of about the same size and type as the body yarn.
It is also known to knit fabric of wool yarn and to then full this fabric to make it substantially ravelproof. This type of fabric has been used in forming the cover material for tennis balls and is illustrated in U.S. Pat. No. 2,018,559.
U.S. Pat. No. 4,255,819 discloses an athletic type sock knit of non-feltable body yarn and with a feltable wool yarn being knit with the body yarn in the heel, sole and toe area. The sock is then subjected to a fulling treatment so that the wool fibers are felted to make the heel, sole and toe dense. The fulling treatment also limits the stretchability of the heel, sole and toe portions of the sock so that these portions of the sock do not provide a comfortable fit on the foot of the wearer. Additionally, the fulling operation adds a separate step to the manufacture of the sock and thereby increases the cost of producing the sock.